Many people know that you cannot squeeze a boil on the face with your hands. We must first understand what is the “danger triangle” of the face. The triangle from the corner of the mouth to the root of the nose is called the danger triangle of the face. The distribution of veins and arteries in the maxillofacial region is basically the same. And they form two networks, deep and superficial, respectively. The deep venous network is not only connected with the branches of superficial veins, but also with the orbital and cranial cavernous sinuses. The facial veins have a characteristic that there is no valve in the venous cavity, the general valve can prevent the reflux of blood, but the facial veins do not have this function, when the muscle contraction, the blood can reflux. Therefore, if an infection occurs on the face, especially if there is a canker sore in the triangle from the corners of the mouth to the root of the nose, you should not squeeze the pus with your hands, otherwise, the bacteria in the canker sore can spread retrogradely to the cavernous sinus in the cranial cavity and form serious brain complications, which can be life-threatening due to the rapid onset of the disease. When you have facial boils and carbuncles, keep the area clean and apply 2% tincture of iodine topically at an early stage; if there is pus, you should go to the local hospital and ask the doctor to deal with it in time, and use some antibiotics. Do not use unclean needles or sharp instruments to release the pus by yourself, otherwise you will lose a lot of money due to the smallness.